【Native Speaker每日综合训练—43系列】【43-02】科技 Mutualism

cherry6891

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Part I: Speaker

Reindeer Spit Smacks Down Plant Toxins
Compounds in reindeer and moose saliva interfere with the production of toxins in plants that ordinarily stop animals from dining on the vegetation. Karen Hopkin reports
October 3, 2014 |By Karen Hopkin
Reindeer spit is in the news. Well, now it is. You see, reindeer and moose eat plants that contain toxins entrusted with keeping the vegetation from being so desirable. But now we know that the animals’ saliva can prevent the production of those toxins. The slick finding is in the journal Biology Letters. [Andrew J. Tanentzap, Mark Vicari and Dawn R. Bazely Ungulate saliva inhibits a grass–endophyte mutualism]

Generally speaking, plants do not like to be eaten. And many have defenses to avoid this fate. The red fescue that’s favored by European reindeer and moose maintains a mutually beneficial relationship with a fungus. When the host plant gets munched on, the resident fungus churns out a toxin called ergovaline. This chemical restricts blood flow to the grazer’s extremities, which can lead to the loss of limbs.

But the battle doesn’t end there. Because researchers found that when reindeer and moose drool is dribbled over plants, ergovaline production goes way down.

The specific secret of the spit is still unsolved. But the researchers think that compounds in the saliva interfere with the chemical signals that switch on toxin production when the plants get ‘et. One thing they know for sure: as they write in their report, and who can argue, the “salivary secretions of large mammals are more important than previously realized.”
source:
http://www.scientificamerican.com/podcast/episode/animal-mimics-more-than-just-camouf-10-01-05/
[Rephrase 1, 1'22'']

cherry6891

Part II: Speed

Time2
Introduction：
Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits. Similar interactions within a species are known as co-operation. Mutualism can be contrasted with interspecific competition, in which each species experiences reduced fitness, and exploitation, or parasitism, in which one species benefits at the expense of the other. Mutualism is a type of symbiosis. Symbiosis is a broad category, defined to include relationships that are mutualistic, parasitic, or commensal. Mutualism is only one type.

A well-known example of mutualism is the relationship between ungulates (such as Bovines) and bacteria within their intestines. The ungulates benefit from the cellulase produced by the bacteria, which facilitates digestion; the bacteria benefit from having a stable supply of nutrients in the host environment.

Mutualism plays a key part in ecology. For example, mutualistic interactions are vital for terrestrial ecosystem function as more than 48% of land plants rely on mycorrhizal relationships with fungi to provide them with inorganic compounds and trace elements. In addition, mutualism is thought to have driven the evolution of much of the biological diversity we see, such as flower forms (important for pollination mutualisms) and co-evolution between groups of species.However mutualism has historically received less attention than other interactions such as predation and parasitism.

Measuring the exact fitness benefit to the individuals in a mutualistic relationship is not always straightforward, particularly when the individuals can receive benefits from a variety of species, for example most plant-pollinator mutualisms. It is therefore common to categorise mutualisms according to the closeness of the association, using terms such as obligate and facultative. Defining "closeness," however, is also problematic. It can refer to mutual dependency (the species cannot live without one another) or the biological intimacy of the relationship in relation to physical closeness (e.g., one species living within the tissues of the other species).
The term "mutualism" was introduced by Pierre-Joseph van Beneden in 1876.[320 words]

source:
http://en.wikipedia.org/wiki/Mutualism_(biology)

Of Ants, Elephants and Acacias: A Tale of Ironic Interdependence
Without large grazing herbivores to eat them, acacia trees suffer because of a shift in the ant populations they house
January 10, 2008 |By David Biello
Time3
Acacia trees are the iconic shrub of the East African savanna. Their thorny thickets house a host of creatures and provide sustenance to the local charismatic megafauna, from elephants to zebras. In light of this continual foraging, the plants have struck a mutually beneficial bargain with several species of ants. The insect armies swarm intrusive browsers in exchange for housing and food. But according to new research in Science, it appears that without such browsing—a state of affairs the acacia might be thought to long for—the trees suffer.

Zoologist Todd Palmer and his colleagues examined the interdependence of one such acacia species—the whistling thorn tree, Acacia drepanolobium—the ants it hosts and the herbivores that eat it. He compared six such trees in Kenya that have been surrounded by an electrified fence since 1995 (by entomologist Truman Young of the University of California, Davis) with six trees open to local giraffes, elephants and other acacia-eaters.

In the absence of herbivores, the whistling acacia stopped producing little ant houses in hollow thorns—known as domatia—and excreting the sweet nectar that its bodyguard ants eat. But instead of spurring more growth, the acacias found themselves more than twice as likely to be providing a home to another type of ant—Crematogaster sjostedti—which do not defend the trees and rely on invasions of the bark-boring cerambycid beetle larvae to build the holes in which they dwell. "The cavity-nesting antagonistic ants actually promote the activities of the stem-boring beetle," says biologist Robert Pringle of Stanford University.

This, in turn, stunts the trees' growth and causes them to die twice as often than when they are being regularly eaten by giraffes, elephants and other large African herbivores. "The trees are actually making a shortsighted decision by defaulting on their end of the mutualism bargain," Pringle says. "If they sustained production of ant rewards in the absence of large mammals, they would reduce their probability of being taken over by this somewhat nasty antagonistic ant."[334 words]

Time4
This counterintuitive result may apply only to the whistling thorn acacia, one of the only species of that genus in Africa that relies on ants as bodyguards rather than thorns and / or chemical defenses. After all, in the wake of disappearing large mammals across Africa, these other types of acacia have proliferated, says ecologist Jacob Goheen of the University of British Columbia.

But it does provide an example of how the disappearance or extinction of elephants, giraffes, zebras and other large herbivores in a region can have unexpected and unintended consequences—much like the boom in leaf-eating beetles and the lizards that prey on them shown in earlier work—whereas the decline of such mammals continues nearly continent-wide through the loss of habitat and overhunting.

"Large herbivores are tremendously important players in these systems," Pringle says. "Not just because of the direct effects they have upon plants, but also because of the myriad effects they exert on smaller, less conspicuous components of biodiversity." For want of an elephant, a protective ant species diminished and left the whistling thorn acacia in dire straits.[183 words]
source:
http://www.scientificamerican.com/article/of-ants-elephants-and-acacias/

More Food from Fungi? Crop-Enhancing Microbes Challenge Genetic Engineering
Researchers investigate how fungi and other symbiotic microbes could improve plants
Apr 1, 2010 |By Michael Tennesen
Time5
To feed an exploding global population, scientists have called for a doubling of food production over the next 40 years. Genetic manipulation might seem the best way to quickly boost characteristics essential to plant growth and crop yields. New findings from different laboratories, however, suggest that fungi, bacteria and viruses could be an exciting alternative to increase agricultural productivity.

Scientists have long known that microbes can work symbiotically with plants. For instance, mycorrhizal fungi, which are associated with 90 percent of land plants, extend from roots to bring in moisture and minerals in exchange for plant carbohydrates. But microbes have recently been found among plant cells themselves and seem to confer benefits, such as more efficient photosynthesis and increased ability to fix nitrogen from the air. In fact, Mary E. Lucero, a biologist at the U.S. Department of Agriculture’s Jornada Experimental Range in Las Cruces, N.M., believes that plants actively recruit these microbes rather than simply being passive hosts for them.

In the lab, Lucero has given this recruitment a hand by transferring fungi from four-wing saltbush to grama grass, which is important for grazing cattle. The fungi-infused grass grew larger and produced more seed, probably by improving nutrient uptake and water usage, she speculates. Lucero also points out that harnessing microbial help for capturing nitrogen could reduce the need for chemical fertilizers. “It is far easier, more efficient and less expensive to inoculate a plant with a
beneficial fungi than to come up with a genetically modified species,” she remarks.

Rusty Rodriguez, a microbiologist with the U.S. Geological Survey’s Biological Resources Division in Seattle, is trying to tackle another agricultural demon: excessive heat. In experiments to improve the ability of tomato plants to resist high temperatures, he inoculated them with fungi taken from plants near hot springs in Yellowstone National Park. The result: tomatoes that can grow at 148 degrees Fahrenheit. “That’s about the internal temperature of a medium cooked prime rib,” Rodriguez notes.[325 words]

Time6
Furthermore, by isolating a virus in the fungus, he discovered a three-way symbiosis that was required for thermal tolerance. “Without the virus the plants could handle only about 100 degrees F,” Rodriguez says. The fungus and virus also conveyed heat tolerance to rice and wheat, a process that could not only boost yields but also help crops fend off the effects of climate change.

Analyzing plants from beaches, deserts and polluted areas, Rodriguez has also isolated microbes that help plants resist salt, drought and heavy metals. Curiously, the same fungi taken from plants living in unstressed areas did not confer tolerance. “It has to be the right microbe from the right habitat,” Rodriguez says. Choosing microbes from heat-stressed areas could boost rice production, which drops 10 percent for every 1.8 degrees F of warming. Once acquired, however, stress-tolerant microbes can be passed in seed coatings to the plant’s progeny.

Christopher L. Schardl, a plant pathologist at the University of Kentucky who studies certain species of tall fescue grass, observes that the mutualism between microbes and plants has agricultural drawbacks, too. Many microbes in plants produce biologically active alkaloids, which repel insects, birds and herbivores. In fact, in the early 1950s grazing livestock picked up a disease related to alkaloids in grass known as fescue toxicosis. It can induce tremor and stupor, as well as an aversion to further grazing. “It costs the livestock industry about $1 billion a year,” says Schardl, adding that producers raising grass-fed cattle are now sowing cultivars with nontoxic fungi.

Identifying plant microbes is not easy, because microbial cells are embedded in plant tissue. Lucero uses scanning electron microscopy and new pyrosequencing techniques to identify the DNA of microbes in plant tissue.[286 words]
source:
http://www.scientificamerican.com/article/more-food-from-fungi/

cherry6891

Part III: Obstacle

Unusual Spider Species Passes Up Live Prey for Plants
A primarily vegetarian jumping spider gets ahead by taking advantage of ancient ant–acacia mutualism
October 12, 2009 |By Katherine Harmon
Time7
Vegetarianism is not exactly what springs to mind when considering spiders, which usually rely on web spinning and other finely tuned techniques to catch and eat other creatures. But one spider has now been observed to feed mostly on plants, shattering the common assumption that all spiders are strict carnivores.

Of the 40,000-plus spider species known, only a few nibble on plants—typically, as a dietary supplement of nectar or simply as an accidental ingestion of pollen. A new paper, published online today in Current Biology, details the natural history of Bagheera kiplingi, a jumping spider that has vegetarian leanings, and its interesting arrangement with a plant and the ants that protect it.  

Certain acacia plants (Vachellia collinsii) and ants (Pseudomyrmex peperi) have developed a mutually beneficial arrangement. The plant provides hollow areas for the ants to nest, along with nutritious nuggets, called Beltian bodies, for them to eat. For their part, the ants help to fend off would-be plant eaters. The crafty B. kiplingi, however, has thwarted the system—also feasting on the plant while managing to outmaneuver attacking ants.

The spider, which lives on these acacias in Latin America, was first described in 1896 by the husband-and-wife naturalist team George and Elizabeth Peckham and named for Rudyard Kipling and the black panther character, Bagheera, in the author's 1894 Jungle Book. The fierce namesake, however, may have proved to be a misnomer for this largely herbivorous arachnid, which went scurrying about its business largely unheeded for more than a century until two researchers observed its unusual feeding habits.

The spider's strange behavior was noted independently in the field by Eric Olson, a lecturer in biology at Brandeis University, in Costa Rica in 2001 and by Christopher Meehan, then a biology master's student at Villanova University, on a field exercise in Mexico in 2007. Waking early for a field research assignment, Meehan decided to observe a jumping spider he saw on an ant-covered acacia—a type of spider that had fascinated him since boyhood.

"I was waiting, expecting it to eat an ant," says Meehan, now a doctoral candidate in the Department of Ecology & Evolutionary Biology at the University of Arizona in Tucson. But rather than nabbing an ant, he says, it struck the plant and went after a Beltian body—"it grabbed the vegetable and ran away and sat on the leaf and ate [it]. I knew it was something unique, but I'd never heard of a vegetarian spider," he says, calling the whole experience "surreal." Expecting what he had seen to be an aberration, he was surprised to witness more spiders doing the same. Once Meehan and Olson heard of each other's findings, they began collaboration on this new research.

Grabbing and eating the Beltian bodies—the spider also eats nectar and ant larvae—isn't terribly different than ingesting a more traditional piece of prey, Meehan says, but it is the digestion process that has the researchers tied up in knots. Chemical analysis of the Beltian bodies shows them to be 80 percent fiber, and "they're not by any means nutrient rich in the same sense as animal tissue," Meehan says. What might allow a formerly carnivorous animal to adapt to a mostly plant diet?

Meehan notes that the peculiar food choice may have gotten started as these arachnids fed on the ant larvae, which are, themselves, fed primarily Beltian bodies. Researchers are now looking for bacteria in these ant larvae that would help the spiders digest the plant material. They also hope to establish whether such bacteria are now passed along to spider offspring or if they must be acquired individually by eating the ant larvae.

Despite their unusual meals, these spiders still exhibit some more traditional hunting behavior. "They're like miniature cats," Meehan says. "They literally stalk and hunt the plant," perhaps lending validity to B. kiplingi's feline namesake. They also use their quick movements to evade would-be ant attackers.

The plant-based diet does, however, seem to have changed this spider's interactions with its neighbors. Individuals can live in close proximity to one another like other species of social spiders, but in other species the spiders are assumed to be cooperating in the hunt (a behavior that, researchers hypothesize, can lead to more sophisticated social organizations). But in the case of B. kiplingi, in which food is simply harvested from the plant, no cooperation is needed, raising the question of why they live in such close quarters. Meehan proposes that the social behavior might be "to reduce local resource competition and reduce aggression," which would be important in instances where some plants are covered with thousands of these spiders.

As for the plants that the spiders feed on, most don't appear to be under severe stress by the arachnid attacks. Some acacias in Mexico, however, that have heavier loads of spiders might be suffering from decreased ant protection, Meehan notes. With all of those spiders harvesting the Beltian bodies for themselves, there are fewer for the ant larvae and thus fewer ants. This sort of instance raises questions about stabilization of the spider–plant–ant system. "Instead of eating the resource once-removed," like the ants, Meehan says, the spiders "go straight to the source." The eating pattern allows more spiders to subsist on a plant than otherwise could get by eating the ant larvae directly.

Regardless of how these spiders came to be primarily plant-eaters, their continued study will likely illuminate a rare species—one that Meehan calls "more extraordinary than a flying pig"—and the system the produced them. "Co-evolution can have cascading effects," Meehan says. "It can serve as evolutionary stepping-stones for third parties that intercept them." And for this oddly adapted spider, it appears to have been a boon.[957 words]
source:
http://www.scientificamerican.com/article/vegetarian-spider/

TVXQashley

time2   1:51
time3   1:56
time4   0:59
time5   1:42
time6   1:35

obstacle:  5:43

14/1013

gpy1992

Time 2 3'18
Mutualism is the way two organisms of different species exist in a relationship in which each
individual benefits.
Time 3 3'26
Time 4 2'13
Time 5 2'35
Scientists are trying to think about how to use fungi, bacteria or viruses to produce food to  feed
an exploding global population.
Time 6 2'45
an experiment the scientist did for study fungus find  that the fungus and cirus also conveyed heat
tolerance to rice and wheat, a process that could not only boost yields but also help crops fend off
the effects of climate change
Time 7 9'16

cherry6891

43-02
speaker: saliva 口水 唾液，churn out 大量产生，munch 咀嚼，
Fungus help the plant to be not eaten by animal ,however,saliva of mammal can detoxicate
Time 2
Mutualism is the way two organisms of different species exist in a relationship in which individual benefits.
It is one kind of symbiosis,but get less attention than predation and parasitism.
Time3
Acacia tree was protected from herbivores like elephant,zebras and ect. Then the tree stop excreting the sweet nectar the bodyguard like eat. In the end,antagonistic ant occupies the nest and promotes the stem-boring beetle,in return,this cause the tree die twice as often as the trees that are eaten by herbivores.
Time4
Large herbivores are tremendously important player in the ecosystem not just because of the effort they have upon plants ,but also because of the myriad effect they exert on conspicuous biodiversity
Time5
New finding suggests that bacteria and fungi could be an exciting alternative to increase productivity since the bacteria can work symbiotically with plant, for example, the more efficient photosynthesis and the ability to fix nitrogen from air.
Time6
The mutualism of microbes and plants has advantage and drawback, for example ,for the good part,the microbes can increase high temperature resistance to fend off climate change,for the bad part,the microbes can cause livestock sick

Obstacle
Scientist find an interesting phenomenon that spiders eat plants to live which are thought to be carnivores.
Then scientists are trying to find the mutually beneficial arrangement of spider and ant. Spiders eat plant and ant larvae that would provide microbes to help digest plant

兮兮西西

Time2 2’39’10 mutualism is a phenomenon that both spicese benefits from each other, such as ungulantes and bacterian . but the mutualism is not always straightforward.

Time 3 3,38,61 the ironic interdependent between acacia ant and elephant ,without being eaten ,the tree die twice

Time 4 1’38’03 large mammals are important in the ecology system

Time5 2’44’06 microbes in the fungi are beneficial to plants that helps them to grow stronger and become healthier than GM food

Time 6 2’27’00 scientists find that microbes can not only gain heats but also defeat climate changes and even salt and insects repel

O 7’25’03 the jumping spider BK has been found to be the plant-eater and lives together with acacia and ants, forming the plant-ant-spider system
Ther  spider has no difference compared with other spider in …
First found of the spider
The spider lives together but has no cooperation with each other

Stefan00

Time 2 2’01’’55:  What is mutualism. Its status in ecosystem is underestimated. How to define it is problematic.
Time3 :2’28’’00 The ants benefit the tree.
Time 4: 1’02’’46 example of what is mutualism.
Time 5:2’06’’65 fungi may do good to agriculture productivity. plus, help fix the nitrogen. An experiment about tomato.
Time 6:1’39’’43 The microbe has the right function in right place. It also has drawbacks. Herbivores can not eat that kind of plants.
obstacle: 5’18’’11 A special spider which is vegetarian. How it was found,  why it eat plants. The spider-ant-ecosystem.

dakxt1

Time 2
Define mutualism
List one of the well known example of mutualism: ungulates and bacteria;
The function of mutualism in ecology is very important, but received less attention
than other interactions such as predation and parasitism.
It is diffcult to measure fitness benefit to the individuasls in a mutualistic relationship.  

Time 3
One kind of Acacia trees that lived in East African savanna once thought to be mutualism with ants
can no longer retain this situation. The ants may stun the growth of the tree, and the mutualism relationship
will no longer exist.  

Time 4
It proves that the importance of large mammals in East African. Once they extinct, not only the tree,
but also biodiversity will be affected.
  
Time 5
Microbe will play an important role in increasing the productivity.
The function of microbes: they can work symbiotically with plants, they also been found among plant cells and seem to
confer benenfits.  
Also, microbes can help deal with problem of excessive heat.  

Time 6
Also, the fungus and virus convey heat tolerance to rice and wheat, resist salt, drought and heavy metals .
However, it also has drawbacks: the mirocbes can produce a kind of chemestry A, which is toxic to livestock.  

seraph797979

cherry6891 发表于 2014-10-13 22:47
Part II: SpeedTime2
Introduction：
Mutualism is the way two organisms of different speci ...

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